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B. P. THOMPSON.

PROUE$S OF MAKING INGANDESGENTS. No. 333,353. Patented July 12, 1887,.

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UNITED STATES PATENT OFFICE.

EDI/VARD I THOMPSON, OF ELIZABETH, NE? JERSEY.

PROCESS OF MAKING INCANDESCENTS.

SPECIFICATION forming part of Letters Patent No. 366,353, dated July 12,1887.

Application filed September 15, 1886. Serial No. 2l3.577. (No model.)

To all whom it may concern.-

Be it known thatl, EDWARD. P. THOMPSON, a citizen of the United States,residing in Elizabeth, in the county of Union and State of New Jersey,have invented certain new and useful Improvements in the Process ofForming Incandescent Electric-Light Filaments, of which the following isa specification.

The invention relates to the process of depositing carbon uponelectric-light filaments.

The invention consists, in general terms, in applying a hydrocarbonvapor under pressure to a filament while a current of electricity isbeing passed through the same, the object being to cause the hydrocarbonto permeate the filament, thus filling the pores instead of beingdeposited merely upon the surface.

The accompanying drawing illustrates an apparatus adapted to carry outthe invention.

Referring to the figure, A representsa belljar adapted to beplaced upona stand or table, B, and tittightly against the same in any usualmanner. A suitable clamp, c, and bindingscrew 0 may be employed inholding the jar in position. A tube, 0 leads from the belljar and isprovided with a valve, 0 for allowing the air to be expelled therefrom.It is designed that a filament, D, shall be placed within the globe,being held by suitable clamps, (Z d, which are connected with therespective poles of a generator, E, by conductors 1 and 2, the latter ofwhich may include a galvanometer, F. A tube, 9, leads from a tank orvessel, G, to the bell-jar. This tube is employed for conductinghydrocarbon vapor from the vessel or tank G to the bell-jar. Preferablythe tube is covered with asbestus or other heat-retaining substance forthe purpose of preventing the carbon vapor from losing its heat. Thetank containing the hydrocarbon liquid is maintained at a temperaturesufficient to vaporize the same by means of a furnace or lamp, as shownat H. By means of the heat the Vapor may be placed under enormouspressure. A safety-valve, h, may be applied to the tank for the purposeof preventing too great a pressure on the part of the vapor.

In practice the filament is raised to a high temperature by means of anelectric current caused to traverse a circuit including the filament. Atthe same time hydrocarbon vapor is caused to fill the bell-jar, and,being under pressure, it is forced into the pores of the filament,whichare opened by reason of the heat. The galvanometer F serves to indicatethe strength of current being employed, and also by means of itsposition it maybe determined when the filament has obtained the requiredthickness and density.

I claim as my invention- 1. The combination, substantially ashereinbefore set forth, of ajar for receiving an incandescentelectric-light filament, means for placing the filament in an electriccircuit, a source of hydrocarbon vapor, and means for causing said vaporto be held in the jar under pressure.

2. The hereinbefore 4 described process of treating filaments forincandescent electric lights, which consists in applying a hydrocarbonvapor to the same under pressure, and at the same time heating thefilaments by an electric current.

3. The combination, with a bell-jar and means for inclosing anincandescent electric light filament within the same, of an electriccircuit, including the filament, of a vapor supply, an escape-valve, andmeans for maintaining the vapor within thejar under pressure.

In testimony whereof I have hereunto subscribed my name this 17th .dayof August, A. D. 1886.

EDWARD P. THOMPSON.

WVitnesses:

DANL. W. EocnooMB, CHARLES A. TERRY.

